"Am I feared" in macro?

As long as the first spell goes off it should.

Cast spell
use trinket - can't
stop spell

or

cast spell - can't/feared
use trinket - removes fear
stop spell - stop's nothing

But if you get:

Cast spell - can't
use trinket - wasted
stop spell

Then it's a problem. This would happen if you are moving and thus can't cast a spell. If you are already casting a spell it would cancel that spell.

Yes, it will need you to think before using it (Stop moving etc) but it will save 4 of your trinkets if it use'd corectly.

One thing you can do, if you have priests / Warlocks (druids have to but i dont think you will use them that much) is that you can have:

/stopmacro [channeling] in the top, this will then not stop your casting if you are casting ex: Mind Flay, Drain life, Drain Soul and other spells that are channeling.

There will never be a perfect way for this, but you can alteast save some trinkets some times by using this.

I just blow them all at once, but have my healer's bound to two keys, so if it's a healer-only trinket situation (since they always get focused) you still have the trinkets ready for the locks when the inevitable aoe fear happens.